U(VI) adsorption on aquifer sediments at the Hanford Site

Aquifer sediments collected via split-spoon sampling in two new groundwater wells in the 200-UP-1 operable unit at the Hanford Site were characterized and showed typical Ringold Unit E Formation properties dominated by gravel and sand. High iron-oxide content in Fe oxide/clay coatings caused the highest U(VI) adsorption as quantified by batch K(d) values, indicating iron oxides are the key solid adsorbent in the 200-UP-1 sediments that affect U(VI) fate and mobility. Even though U(VI) adsorption on the gravel-sized fraction of the sediments is considered to be negligible, careful characterization should be conducted to determine U(VI) adsorption on gravel, because of presence of Fe oxides coatings and diffusion-controlled adsorption into the gravel particles' interior surfaces. A linear adsorption isotherm was observed up to 10(-6) M (238 microg/L) of total U(VI) concentration in batch U(VI) adsorption tests with varying total U(VI) concentrations in spiked groundwater. U(VI) adsorption decreased with increasing concentrations of dissolved carbonate, because strong anionic aqueous uranium-carbonate complexes formed at high pH and high alkalinity conditions. Noticeable uranium desorption hysteresis was observed in a flow-through column experiment, suggesting that desorption K(d) values for aged uranium-contaminated sediments at the Hanford Site can be larger than adsorption K(d) values determined in short-term laboratory experiments and slow uranium release from contaminated sediments into the groundwater is expected.     

Toxicity of cobalt-complexed cyanide to <Emphasis Type="Italic">Oncorhynchus mykiss,Daphnia magna</Emphasis>, and <Emphasis Type="Italic">Ceriodaphnia dubia</Emphasis>

Background Cobalt cyanide complexes often result when ore is treated with cyanide solutions to extract gold and other metals. These have recently been discovered in low but significant concentrations in effluents from gold leach operations. This study was conducted to determine the potential toxicity of cobalt-cyanide complexes to freshwater organisms and the extent to which ultraviolet radiation (UV) potentiates this toxicity. Tests were also conducted to determine if humic acids or if adaptation to UV influenced sensitivity to the cyanide complexes. Methods Rainbow trout (Oncorhynchus mykiss), Daphnia magna, and Ceriodaphnia dubia were exposed to potassium hexacyanocobaltate in the presence and absence of UV radiation, in the presence and absence of humic acids. Cyano-cobalt exposures were also conducted with C. dubia from cultures adapted to elevated UV. Results With an LC50 concentration of 0.38 mg/L, cyanocobalt was over a 1000 times more toxic to rainbow trout in the presence of UV at a low, environmentally relevant irradiance level (4 μW/cm² as UVB) than exposure to this compound in the absence of UV with an LC50 of 112.9 mg/L. Toxicity was immediately apparent, with mortality occurring within an hour of the onset of exposure at the highest concentration. Fish were unaffected by exposure to UV alone. Weak-acid dissociable cyanide concentrations were observed in irradiated aqueous solutions of cyanocobaltate within hours of UV exposure and persisted in the presence of UV for at least 96 hours, whereas negligible concentrations were observed in the absence of UV. The presence of humic acids significantly diminished cyanocobalt toxicity to D. magna and reduced mortality from UV exposure. Humic acids did not significantly influence survival among C. dubia. C. dubia from UV-adapted populations were less sensitive to metallocyanide compounds than organisms from unadapted populations. Conclusions The results indicate that metallocyanide complexes may pose a hazard to aquatic life through photochemically induced processes. Factors that decrease UV exposure such as dissolved organic carbon or increased pigmentation would diminish toxicity.     

Line transect sampling of Karner blue butterflies ( Lycaeides melissa samuelis)

Line transect sampling is an effective survey method for estimating butterfly densities because it provides unbiased estimates of site-density (provided key assumptions are met), and estimates are comparable among sites. For monitoring Karner blue butterflies in Wisconsin, USA, comparable estimates are required because each year a different selection of sites will be monitored. Annual state-wide indices of species abundance can be derived from the site-surveys and compared to previous year's indices to monitor trends. We advocate that line transect sampling is preferable to Pollard-Yates transects as a survey technique for monitoring Karner blue butter- flies. The Pollard-Yates surveys do not adjust for diferences in site detectability. As a consequence, estimates of among-site from Pollard-Yates surveys can be biased. © Rapid Science 1998     

Evaluating Genetic Diversity Associated with Propagation-Assisted Restoration of American Shad

Abstract: We investigated the conservation of genetic diversity during a restoration program for American shad ( Alosa sapidissima ) in Virginia ( U.S.A.). Restoration entailed capture of wild Pamunkey River shad broodstock followed by production and release of hatchery-reared fry to supplement the nearly extinct James River shad population. To assess the baseline genetic diversity of donor and recipient populations, we used five tri- and tetra-nucleotide microsatellite loci to test for genetic heterogeneity among yearly subsamples from both rivers and between early- and late-spawning shad from the donor population. Tests for allelic heterogeneity between James River and Pamunkey shad subsamples yielded no significant genetic differentiation (χ ² = 14.72, p = 0.132 and χ ² = 10.24, p = 0.440, respectively). We detected no significant genetic divergence between early- and late-spawning adults in Pamunkey River spawning aggregations in either year. The donor and recipient populations exhibited significant genetic differentiation (χ ² = 27.4, p = 0.003), however, indicating that the stocking program carries a risk of outbreeding depression. Because the two river populations are genetically divergent, replenishment of the James population with Pamunkey fry may be detectable in the future as heterozygote deficits and linkage disequilibria in the James River population. In an analysis of broodstock and their hatchery-reared progeny, microsatellites proved efficient for family analysis, unambiguously determining the parentage of 100% of the hatchery-reared fry studied. Genetic analysis indicated that breeding procedures may result in high levels of reproductive variance.     

Why Economics Matters for Endangered Species Protection

Abstract: We offer three reasons why economics matters more to species protection than many people think and what this implies for the ongoing debate over the reauthorization of the Endangered Species Act of 1973. Economics matters because (1) human behavior generally, and economic parameters in particular, help determine the degree of risk to a species; (2) in a world of scarce resources, the opportunity cost of species protection—the costs of reduced resources for other worthwhile causes—must be taken into account in decision making; and (3) economic incentives are critical in shaping human behavior, and consequently the recovery of species. Endangered species protection that explicitly addresses these basic principles can avoid wasting valuable resources that yield no gain in species protection.     

Variation in condition of coastal Newfoundland 0-group Atlantic cod (Gadus morhua): field and laboratory studies using simple condition indices

Demersal 0-group Atlantic cod (Gadus morhua L.) were collected in Trinity Bay, Newfoundland, Canada, between August 1993 and January 1994. Diet composition and simple indices of condition (hepato-somatic index, condition factors and body ash content) were determined. Laboratory experiments were also conducted to determine whether simple indices of condition reflect differences in energy intake (ration level) and to determine minimum index of condition values, assessed from 0-group cod that died due to exhaustion of their energy reserves. Determination of lower critical indices of condition provided a meaningful interpretation of field data on feeding, condition and survival of 0-group cod. In the wild, indices of condition reflecting variation in liver and muscle energy reserves of cod increased rapidly with the consumption of Calanus finmarchicus, which exhibited a high incidence of oil sacs, and declined abruptly when this lipid-rich prey was no longer consumed. Liver and muscle condition of 0-group cod from the field varied seasonally, but their condition was consistently above that of cod that died in the laboratory. Laboratory studies, using three ration levels, revealed that condition indices differed over time and among ration levels. Indices of condition representing variation in muscle energy reserves exhibited a steady decline once the hepato-somatic index fell below about 2.0. We interpret this as evidence for depletion of lipids first and then proteins, a pattern similar to that of larger juveniles and adults. We conclude that as long as 0-group cod are above a “safe” level of condition their body length can still increase even when condition is declining. Received: 2 September 1997 / Accepted: 8 December 1998     

Applying systems thinking concepts in the analysis of major incidents and safety culture

In recent years, investigations into major incidents often highlight poor safety culture as one of the key causal factors. These investigations are often assisted by causal analysis tools that help to ensure that the investigation and the information captured are systematic. However, current causal analysis tools are not designed to analyse dynamic complexity of major incidents and safety culture, which arises from the interactions between actors and the temporal and spatial gaps between actions and consequences. This is because most causal analysis tools model events and causal factors linearly. In contrast, systems thinking, a discipline of seeing systems holistically, emphasises the circular nature of complex systems, i.e. cause and effect are not distinguishable. This paper proposes that traditional causal analysis tools and investigation should be enhanced with the use of systems thinking tools.One of the systems thinking tools that is particularly useful in analysing major incidents and safety culture is causal loop diagrams. The diagrams can be used to explain the systemic structure sustaining a safety culture and identify effective interventions to improve the safety culture and prevent a recurrence of a major incident. The paper demonstrates the use of systems thinking and causal loop diagrams through a case study on Bellevue hazardous waste fire in Western Australia. The case study shows how different actors in the system, each acting in reaction to pressures that they are facing, produced and sustained a poor safety culture that was a major contributory factor to the fire in 2001.     

How long can fisheries management delay action in response to ecosystem and climate change?

Sustainable management of fisheries is often compromised by management delaying implementation of regulations that reduce harvest, in order to maintain higher catches in the short-term. Decreases or increases in fish population growth rate driven by environmental change, including ecosystem and climate change, affect the harvest that can be taken sustainably. If not acted on rapidly, environmental change could result in unsustainable fishing or missed opportunity for higher catches. Using simulation models of harvested fish populations influenced by environmental change, we explore how long fisheries managers can afford to wait before changing harvest regulations in response to changes in population growth. If environmental change causes population declines, delays greater than five years increase the probability of population collapse. Species with fast and highly variable population growth rates are more susceptible to collapse under delays and should be a priority for revised management where delays occur. Generally, the long-term cost of delay, in terms of lost fishing opportunity, exceeds the short-term benefits of overfishing. Lowering harvest limits and monitoring for environmental change can alleviate the impact of delays; however, these measures may be more costly than reducing delays. We recommend that management systems that allow rapid responses to population growth changes be enacted for fisheries management to adapt to ecosystem and climate change.     

Toward an Understanding of the Development of Ownership Feelings

Psychological ownership is increasingly recognized as a core feeling in the experience of work. Within jobs and the work context, there is a wide range of opportunities to experience psychological ownership. Yet empirical work on how feelings of ownership develop is lacking, and thus ways to develop psychological ownership in the workplace are not well understood. We explore the routes traveled to feelings of ownership by using job complexity as one example of work environment structure that affects the formation of psychological ownership. In two studies, we develop measures of the routes and confirm that perceived differences in one's work meaningfully predict psychological ownership. Collectively, the two studies provide insight into and offer suggestions for how ownership develops and ways in which managers might foster employee feelings of ownership toward their work. Copyright © 2013 John Wiley & Sons, Ltd.